Trying to fix a leaky Kohler single knob bath faucet. Took everything apart and replaced the four o-rings I found but still hear water running sounds and little bit of water coming from the spout. Is anyone familiar with this type of repair?

Is it a mixing valve cartridge model?
Went through the same thing last week with my DELTA single handle shower valve. The $3 fix is what you did in replacing o rings and seals. If it still leaks, then it is time for the $40 fix and replace the whole inner cartridge.
I found my DELTA cartridge at the local hardware, surely you can find what you need there for your KOHLER.